U.S. Pat. No. 4,655,658 granted Apr. 7, 1987, inventor: B. Gulistan, is entitled Captive Panel Fastener. This patent discloses a fastener in which the abstract of the patent is useful in describing the fastener by way of background for the present invention. The abstract of the U.S. Pat. No. 4,655,658 will therefore be repeated here:
“A captive panel fastener includes a head, a shank and a threaded outer end, with slots extending longitudinally down through the threads toward the outer end of the fastener. A relatively rigid and inflexible retention washer is provided and this washer has inwardly extending prongs that fit into the longitudinally extending slots on the fastener. The outer end of the fastener has a hole in it, and after the washer is in place a forming tool is employed to deform the outer end wall of the opening so that the wall is pushed outwardly to block the outer ends of the longitudinally extending slots, thereby holding the washer onto the fastener, and retaining it extending through a hole in a panel or the like through which it may have been inserted. A small washer may be employed at the end of the fastener between the ends of the slots and the deformed extreme outer end of the fastener.”
On occasion, for example when the threads of the fastener are damaged, it would be desirable to replace the fastener at a field maintenance location. However, the installation of the captive fastener as described above requires a special forming tool, to deform the outer end wall of the fastener to hold the retention washer in place. It is impractical to provide each field maintenance location with the required special forming tool, and accordingly the aircraft or other equipment using the fastener is often used with the damaged fastener; and replacement is not accomplished until the aircraft returns to a major maintenance location where the forming tool is available.